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baby bottle tooth decay: Also known as severe early childhood caries. A severe pattern of dental caries in infants and young children that first attacks the upper front teeth.

bacillus: A bacterium that has a straight rod-like shape.

bacteria: A group of one-celled microorganisms that are mostly disease producing.

bicuspid (premolar): One of the two permanent teeth located in front of the molars and behind each cuspid. These teeth have two cusps (points) and are used to tear and grind food.

bolus: A chewed, soft mass of food.

buffer: A substance that helps regulate or stabilize the pH of a solution during chemical reactions.

carbohydrate: A main source of energy for our body that is composed of starches and sugars. Carbohydrates are found predominantly in breads, cereals, fruits, and vegetables.

caries (dental caries): The bacterial disease known as tooth decay or cavities that causes demineralization of teeth through frequent exposure to sugars and starches.

cavity (carious lesion): An area of the tooth affected by dental caries.

cementum: A layer of bone-like mineralized tissue that covers the roots of a tooth.

cleft lip and/or palate: A malformation present at birth where the lip or palate fails to fuse. A cleft lip and/or palate require surgical correction.

coccus: A bacterium that is spherical in shape.

control: Person(s) or object in an experiment selected to be like the experimental subject except for the variable being tested.

craniofacial: That which is involved or related to the skull and the face.

crown: The part of the tooth covered with enamel and protruding above the gum line.

cuspid (canine): A sharp, pointed tooth used for tearing food; located between the first bicuspid and the lateral incisor.

deciduous teeth: See primary teeth.

demineralization: Process of mineral loss from the enamel during the early stages of dental caries. The mineral loss results in chalky white or opaque patches on the tooth surface.

dentin: A tissue, hard and bone-like, that forms most of the tooth.

dextran: An oral bacteria waste product that is sticky and adheres to the tooth, creating a film called plaque.

digestive enzymes: Enzymes that speed the process of breaking large food molecules into smaller units that are absorbed into the cells.

enamel: The visible outer layer of the tooth.

environment: Everything in the surroundings of an organism; living and nonliving surroundings and factors including light, temperature, air, soil, water, and organisms.

enzyme: A catalyst produced by an organism and used to speed up a specific kind of chemical reaction.

esophagus: The tubular portion of the digestive tract that leads from the pharynx to the stomach.

facial nerve (cranial nerve VII): Nerve that supplies sensory and parasympathetic fibers to the tongue, palate, and the narrow passage from the mouth, and motor fibers to the muscles of the face and jaw.

fluoride: A mineral that is effective in preventing and reversing the early signs of dental caries. Fluoride occurs naturally and contains the element fluorine.

frenulum: A small fold of tissue that connects a more fixed part, such as the floor of the mouth, to a movable part, like the tongue.

fructose: Known as fruit sugar; a member of the simple sugars carbohydrate group found in fruits, honey and syrups, and certain vegetables.

gingiva (gums): The tissue that surrounds the neck of the tooth and covers the alveolar bone.

gingivitis: Gum inflammation caused by the buildup of plaque along the gum line.

glucose: A member of the simple sugar carbohydrate group that is found in fruits and honey. Glucose is the most common free sugar that circulates in the blood of higher animals.

incisor: One of the four front teeth on the upper and lower jaw.

malocclusion: Teeth that are misaligned or fit together poorly when the jaws are closed.

mamelon: A small bump on the biting surface of an incisor tooth when it first appears in the mouth. Normal chewing and biting usually wear down mamelons to leave a smooth tooth edge.

microorganism: An organism too small to be seen with the unaided eye, such as bacteria, viruses, unicellular algae, and protozoans.

model: Something that is used as the foundation for a similar idea or process.

molar: A tooth located in the back of the mouth used for crushing and grinding food. There are usually three permanent molars on each side of the jaws. There are two primary molars on each side of the jaw.

mumps: A viral infection that causes the salivary glands, especially the parotid gland, to swell.

olfactory system: Anything connected with or relating to the sense of smell.

oral cavity: The inside of the mouth, bounded by the palate, teeth, and tongue.

oral hygiene: Activities that promote good health of the mouth.

palate: The roof of the mouth; the partition between the oral and nasal cavities that is formed by the hard palate and the soft palate.

papilla: One of the small bumps on the upper surface of the tongue. (papilla, singular; papillae, plural)

permanent teeth: The second and final set of teeth to appear in the mouth, consisting of 32 teeth.

pH scale: A scale from 0 to 14 reflecting the concentration of hydrogen ions in solution; the lower numbers denote acidic conditions and the upper numbers denote basic, or alkaline, conditions.

pharynx: The area where the air and food passages cross; found in the throat of vertebrates.

pits and fissures: Dimples (pits) and creases (fissures) found on six-and twelve-year molars, and premolar teeth. Pits also may be found on the back surfaces of upper front teeth.

plaque: A sticky, thin film that is made up of a protein substance and microorganisms that adhere to the tooth.

prediction: To foresee using observation, experience, or scientific reason.

primary teeth: The first set of teeth. This set of 20 teeth is also known as baby, deciduous, or milk teeth.

pulp chamber: The tooth's innermost part containing blood vessels, cells, and nerves.

remineralization: The reversal of demineralization of tooth enamel.

root: The part of the tooth that anchors it to the bone and is normally beneath the gum.

saliva: The watery liquid secreted into the mouth from the salivary glands.

salivary gland: An organ that secretes saliva.

scientific inquiry: The process by which scientists ask questions, develop and carry out investigations, make predictions, gather evidence, and propose explanations.

sealants: Thin coatings made of plastic applied to the chewing surfaces of back teeth to prevent decay.

sensory organs: Organs that are capable of receiving and responding to outside information (stimulus).

six-year molars: The first permanent molar teeth to come into the mouth.

speech pathologist: A person who studies the irregularities of speech.

starch: A complex carbohydrate made up of many glucose molecules linked together and found in foods like potatoes, wheat, rice, and corn.

sucrose: Also known as white or table sugar. Sucrose is made up of two simple sugar units: glucose and fructose. Sucrose occurs naturally in many green plants as a product of photosynthesis.

taste bud: A sense organ found primarily on the tongue's upper surface consisting of small flask-shaped groups of cells.

tongue: Movable organ on the floor of the mouth.

tooth decay: See caries.

uvula: The fleshy structure hanging from the center of the soft palate.

waste product: A byproduct (such as urine or feces) that is discharged from a living body.

white spot: A chalky or opaque patch on the tooth surface resulting from early loss of minerals from the tooth enamel. White spots can be precursors to cavities if proper oral hygiene and diet are not followed.

wisdom tooth: The third molar found in each jaw.

x-ray: A photograph that reveals details not normally visible.

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